1. Technical Field
This invention in general relates to computer systems. More specifically, this invention relates to a disk system or interface that can be directly attached to a network.
2. Description of the Related Art
As the Internet becomes popular, the amount of data that needs to be stored has drastically increased. Especially, there is a high demand for a high-capacity disk drive to store multimedia data. For example, a demand for a disk system having a disk capacity of terabytes per server is not unusual.
A tape drive or a CD drive may be used to store such amount of data, but its performance and user convenience are not matched to those of a hard disk drive. However, increasing the capacity of a hard disk in a conventional server system presents some problems.
There are NAS (Network Attached Storage) products that can be connected to a network, usually Ethernet, to provide a pre-configured disk capacity along with integrated system/storage management using the NFS (Network File System) protocol, the CIFS (Common Internet File System) protocol, or both on top of the IP protocol used on the Internet. The primary purpose of these protocols is to exchange files between independently operating computers. Therefore, the client using the NAS for file access experiences the difference between its local storage and the storage in the NAS systems.
The NAS is basically a stripped-down version of a file server having mainly the functions of storing and retrieving files. Accordingly, increasing a disk capacity using a NAS product amounts to adding a separate file server in practice, which presents many shortcomings. Since an NAS disk is not seen as a local disk to the client, the installation, movement, and administration of an NAS disk should be done only through the operating system and software offered as part of the NAS system. An NAS disk is installed in the inside bus of the NAS system, leading to a limitation to the number of disks that can be installed. Since the NAS system has a hard disk under its own operating system, the client cannot use an arbitrary file system to access the hard disk. Further, the NAS system requires an IP address. Overall, not only the installation and administration costs per disk are more expensive than those of a local disk, but also user convenience is severely restricted.
There is SAN (Storage Area Network) that uses the Fibre Channel technology. To use the devices connected to a SAN, a special-type of switch is needed. For example, Fiber Channel uses a Fibre Channel hub or a Fibre Channel switch. The SAN has some shortcomings. Typically, a separate file server is used. In general, the SAN equipment is expensive, and so is the administration cost of the SAN system because, for example, it often requires an administrator with a specialized knowledge on the system.
Therefore, there is a need for an interface that allows a disk system to be directly attached to a network, while still being accessed like a local disk without the need of adding an additional file server or special equipment.